Transcript week1-ee522x

EE 522: Wireless Communications
Dr. Ghazi Al Sukkar
email: [email protected]
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Course Information:
 Instructor: Dr. Ghazi Al Sukkar.
 Email: [email protected]
 Office: E315
 Website: www2.ju.edu.jo/sites/acadimic/ghazi.alsukkar
 Office Hours: See website.
 Prerequisites: EE421 Preferred EE422 and EE426
 Textbook: Wireless Communications, Principles and
Practice. 2nd edition or above, Theodore S. Rappaport.
 References:
 Wireless and Cellular Telecommunications, 3rd edition,
William C. Y. Lee, 2006.
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Course Syllabus:
 Introduction: Wireless Communicatios.
 Cellular Networks principles:
 2G systems: GSM:
 Spread Spectrum Techniques.
 3G systems: UMTS
 Orthogonal Frequency Division Multiplexing.
 4G systems: LTE-Advance
 For details see:
http://www2.ju.edu.jo/sites/Academic/ghazi.alsukkar
/Material/Forms/AllItems.aspx
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Introduction Outline:
 The Wireless Vision
 Technical Challenges
 Current Wireless Systems
 Emerging Wireless Systems
 Spectrum Regulation
 Standards
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Wireless History
 Ancient Systems: Smoke Signals, Carrier Pigeons, …
 Radio invented in the 1880s by Marconi
 Many sophisticated military radio systems were
developed during and after WW2
 Cellular has enjoyed exponential growth since
1988, with almost 6 billion users worldwide today
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Ignited the wireless revolution
Voice, data, and multimedia becoming ubiquitous
Use in third world countries growing rapidly
 Wifi also enjoying tremendous success and growth

Wide area networks (e.g. Wimax) and short-range
systems other than Bluetooth (e.g. UWB) less successful
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Future
Wireless
Networks
Ubiquitous Communication Among People and Devices
-Next-generation Cellular
-Wireless Internet Access
-Wireless Multimedia
-Sensor Networks
-Smart Homes/Spaces
-Automated Highways
-In-Body Networks
All this and more … 6
Challenges
 Network Challenges
 Scarce spectrum
 Demanding/diverse applications
 Reliability
 Ubiquitous coverage
 Seamless indoor/outdoor operation
 Device Challenges
 Size, Power, Cost
 Multiple Antennas in Silicon
 Multiradio Integration
 Coexistance
BT
Cellular
FM/XM
GPS
DVB-H
Apps
Processor
WLAN
Media
Processor
Wimax
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Software-Defined (SD) Radio:
Is this the solution to the device challenges?
BT
Cellular
FM/XM
A/D
GPS
DVB-H
Apps
Processor
WLAN
Media
Processor
Wimax
A/D
A/D
DSP
A/D
 Wideband antennas and A/Ds span BW of desired signals
 DSP programmed to process desired signal: no specialized HW
Today, this is not cost, size, or power efficient
Compressed sensing may be a solution for sparse signals
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Evolution of Current Systems
 Wireless systems today
 3G Cellular: ~200-300 Kbps.
 WLANs: ~450 Mbps (and growing).
 Next Generation is in the works
 4G Cellular: OFDM/MIMO
 4G WLANs: Wide open, 3G just being finalized
 Technology Enhancements
 Hardware: Better batteries. Better circuits/processors.
 Link: More bandwidth, more antennas, better modulation and
coding, adaptivity, cognition.
 Network: better resource allocation, cooperation, relaying,
femtocells.
 Application: Soft and adaptive QoS.
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Future Generations
Rate
802.11n
802.11b WLAN
2G
4G
3G
Other Tradeoffs:
Rate vs. Coverage
Rate vs. Delay
Rate vs. Cost
Rate vs. Energy
Wimax/4G
3G
2G Cellular
Mobility
Fundamental Design Breakthroughs Needed
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Multimedia Requirements
Voice
Data
Video
Delay
<100ms
-
<100ms
Packet Loss
BER
<1%
10-3
0
10-6
<1%
10-6
Data Rate
Traffic
8-32 Kbps 10-1000 Mbps 10-1000 Mbps
Continuous
Bursty
Continuous
One-size-fits-all protocols and design do not work well
Wired networks use this approach, with poor results 11
Quality-of-Service (QoS)
 QoS refers to the requirements associated with a
given application, typically rate and delay
requirements.
 It is hard to make a one-size-fits all network that
supports requirements of different applications.
 Wired networks often use this approach with
poor results, and they have much higher data
rates and better reliability than wireless.
 QoS for all applications requires a cross-layer
design approach.
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Crosslayer Design
 Application
 Network
 Access
 Link
 Hardware
Delay Constraints
Rate Constraints
Energy Constraints
(physical)
Adapt across design layers
Reduce uncertainty through scheduling
Provide robustness via diversity
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Current Wireless Systems
 Cellular Systems
 Wireless LANs
 Wimax
 Satellite Systems
 Paging Systems
 Bluetooth
 Zigbee radios
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Cellular Phones
Everything Wireless in One Device
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First Mobile Radio Telephone1924
Courtesy of Rich Howard
Cellular Systems:
Reuse channels to maximize capacity
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Geographic region divided into cells
Frequency/timeslots/codes/ reused at spatially-separated locations.
Co-channel interference between same color cells.
Base stations/MTSOs coordinate handoff and control functions
Shrinking cell size increases capacity, as well as networking burden
BASE
STATION
MTSO
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Cellular Networks
San Francisco
BS
BS
Internet
Nth-Gen
Cellular
Phone
System
Nth-Gen
Cellular
New York
BS
Future networks want better performance and reliability
- Gbps rates, low latency, 99% coverage indoors and out
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3G Cellular Design: Voice and Data
 Data is bursty, whereas voice is continuous
 Typically require different access and routing strategies
 3G “widens the data pipe”:
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384 Kbps (802.11n has 100s of Mbps).
Standard based on wideband CDMA
Packet-based switching for both voice and data
3G cellular popular in Asia and Europe
 Evolution of existing systems in US (2.5G++)
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GSM+EDGE, IS-95(CDMA)+HDR
100 Kbps may be enough
Dual phone (2/3G+Wifi) use growing (iPhone, Google)
 What is beyond 4G?
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4G/LTE/IMT Advanced
 Much higher peak data rates (50-100 Mbps)
 Greater spectral efficiency (bits/s/Hz)
 Flexible use of up to 100 MHz of spectrum
 Low packet latency (<5ms).
 Increased system capacity
 Reduced cost-per-bit
 Support for multimedia
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1G to 4G cellular standards
http://www.gsma.com/hspa/
http://www.cdg.org/index.asp
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Mobile Standard Organizations
Mobile
Operators
ITU Members
ITU
IS-95), IS-41, IS2000, IS-835
GSM, W-CDMA,
UMTS
Third Generation
Patnership Project
(3GPP)
CWTS
(China)
Third Generation
Partnership Project II
(3GPP2)
ARIB
(Japan)
TTC
(Japan)
TTA
(Korea)
ETSI
(Europe)
T1
(USA)
TIA
(USA)
Partnership Project and Forums
 ITU IMT-2000 http://www.itu.int/imt2000
 Mobile Partnership Projects
 3GPP: http://www.3gpp.org
 3GPP2: http://www.3gpp2.org
 Mobile Technical Forums
 3G All IP Forum: http://www.3gip.org
 IPv6 Forum: http://www.ipv6forum.com
 Mobile Marketing Forums
 Mobile Wireless Internet Forum: http://www.mwif.org
 UMTS Forum: http://www.umts-forum.org
 GSM Forum: http://www.gsmworld.org
 Universal Wireless Communication: http://www.uwcc.org
 Global Mobile Supplier: http://www.gsacom.com
Mobile Standards Organizations
 European Technical Standard Institute (Europe):
 http://www.etsi.org
 Telecommunication Industry Association (USA):
 http://www.tiaonline.org
 Standard Committee T1 (USA):
 http://www.t1.org
 China Wireless Telecommunication Standard (China):
 http://www.cwts.org
 The Association of Radio Industries and Businesses (Japan):
 http://www.arib.or.jp/arib/english/
 The Telecommunication Technology Committee (Japan):
 http://www.ttc.or.jp/e/index.html
 The Telecommunication Technology Association (Korea):
 http://www.tta.or.kr/english/e_index.htm
The way from 2G to 4G
IS-136
& PDC
GSM
IS-95
2G
GPRS
CAMEL
IS-95B
EDGE
Cdma20001xRTT
3GPP2
Cdma2000-1xEV, DV, Do
TD-SCDMA
2.5G
WCDMA
(UMTS)
3GPP
3G
Cdma2000-3xRTT
HSPA+
LTE, LTE-advanced
HSPA
3.5G
4G
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WLAN
Multimedia Everywhere, Without Wires
802.11n++
• Streaming video
• Gbps data rates
• High reliability
• Coverage in every room
Wireless HDTV
and Gaming 26
Wireless Local Area Networks (WLANs)
01011011
0101
1011
Internet
Access
Point
WLANs connect “local” computers (100m range)
 Breaks data into packets
 Channel access is shared (random access) CSMA/CA
 Backbone Internet provides best-effort service
 Poor performance in some apps (e.g. video)

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Wireless LAN Standards
 802.11b (Old – 1990s)
 Standard for 2.4GHz ISM band (80 MHz)
 Direct sequence spread spectrum (DSSS)
 Speeds of 11 Mbps, approx. 500 ft range
 802.11a/g (Middle Age– mid-late 1990s)
 Standard for 5GHz band (300 MHz)/also 2.4GHz
 OFDM in 20 MHz with adaptive rate/codes
 Speeds of 54 Mbps, approx. 100-200 ft range
Many
WLAN
cards
have
all 3
(a/b/g)
 802.11n (young pup)
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Standard in 2.4 GHz and 5 GHz band
Adaptive OFDM /MIMO in 20/40 MHz (2-4 antennas)
Speeds up to 600Mbps, approx. 200 ft range
Other advances in packetization, antenna use, etc.
What’s next?
802.11ac/ad
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Wimax (802.16)
 Worldwide Interoperability for Microwave Access (Wimax)
 Wide area wireless network standard
 System architecture similar to cellular
 Called “3.xG” (e.g. Sprint EVO), evolving into 4G
 OFDM/MIMO is core link technology
 Operates in 2.5 and 3.5 GHz bands
 Different for different countries, 5.8 also used.
 Bandwidth is 3.5-10 MHz
 Fixed (802.16d) vs. Mobile (802.16e) Wimax
 Fixed: 75 Mbps max, up to 50 mile cell radius
 Mobile: 15 Mbps max, up to 1-2 mile cell radius
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WiGig and Wireless HD
 New standards operating in 60 GHz band
 Data rates of 7-25 Gbps
 Bandwidth of around 10 GHz (unregulated)
 Range of around 10m (can be extended)
 Uses/extends 802.11 MAC Layer
 Applications include PC peripherals and displays for
HDTVs, monitors & projectors
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Satellite Systems
 Cover very large areas
 Different orbit heights
 GEOs (39000 Km) versus LEOs (2000 Km)
 Optimized for one-way transmission
 Radio (XM, Sirius) and movie (SatTV, DVB/S) broadcasts
 Most two-way systems struggling or bankrupt
 Global Positioning System (GPS) use growing
 Satellite signals used to pinpoint location
 Popular in cell phones, PDAs, and navigation devices
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Paging Systems
 Broad coverage for short messaging
 Message broadcast from all base stations
 Simple terminals
 Optimized for 1-way transmission
 Answer-back hard
 Overtaken by cellular
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Bluetooth
 Cable replacement RF technology (low cost)
 Short range (10m, extendable to 100m)
 2.4 GHz band (crowded)
 1 Data (700 Kbps) and 3 voice channels, up to 3 Mbps
 Widely supported by telecommunications, PC, and
consumer electronics companies
 Few applications beyond cable replacement
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IEEE 802.15.4/ZigBee Radios
 Low-Rate WPAN and WBAN
 Data rates of 20, 40, 250 Kbps
 Support for large mesh networking or star clusters
 Support for low latency devices
 CSMA-CA channel access
 Very low power consumption
 Frequency of operation in ISM bands
Focus is primarily on low power sensor networks
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Tradeoffs
Rate
802.11n
3G
802.11g/a
Power
802.11b
UWB
Bluetooth
ZigBee
Range
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Mobility vs. Technology
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Range vs. Technology
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EM Spectrum
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EM Spectrum
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EM Bands
Legend:
γ = Gamma rays
HX = Hard X-rays
SX = Soft X-Rays
EUV = Extreme-ultraviolet
NUV = Near-ultraviolet
Visible light
NIR = Near-infrared
MIR = Moderate-infrared
FIR = Far-infrared
Used bands for mobile
communication
Radio waves:
EHF = Extremely high frequency (Microwaves)
SHF = Super-high frequency (Microwaves)
UHF = Ultrahigh frequency
VHF = Very high frequency
HF = High frequency
MF = Medium frequency
LF = Low frequency
VLF = Very low frequency
VF = Voice frequency
ULF = Ultra-low frequency
SLF = Super-low frequency
ELF = Extremely low frequency
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Scarce Wireless Spectrum
$$$
and Expensive
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In Jordan:
 Refere to the Telecommunications Regulatory
Commission (TRC) home page
http://www.trc.gov.jo/index.php/doc/index.php?lang=english
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Frequency Allocations chart
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Spectrum Regulation
 Spectrum a scarce public resource, hence allocated
 Spectral allocation in US controlled by FCC
(commercial) or OSM (defense)
 FCC auctions spectral blocks for set applications.
 Some spectrum set aside for universal use
 Worldwide spectrum controlled by ITU-R
 Regulation is a necessary evil.
Innovations in regulation being considered worldwide,
including underlays, overlays, and cognitive radios
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Spectral Reuse
Due to its scarcity, spectrum is reused
In licensed bands
and unlicensed bands
BS
Cellular, Wimax
Wifi, BT, UWB,…
Reuse introduces interference
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Interference: Friend or Foe?
If exploited via
cooperation and cognition
Friend
Especially in a network setting
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Rethinking “Cells” in Cellular
Coop
MIMO
Femto
How should cellular
systems be designed?
Relay
DAS
Will gains in practice be
big or incremental; in
capacity or coverage?
 Traditional cellular design “interference-limited”
 MIMO/multiuser detection can remove interference
 Cooperating BSs form a MIMO array: what is a cell?
 Relays change cell shape and boundaries
 Distributed antennas move BS towards cell boundary
 Femtocells create a cell within a cell
 Mobile cooperation via relays, virtual MIMO, network coding.
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Standards
 Interacting systems require standardization
 Companies want their systems adopted as standard
 Alternatively try for de-facto standards
 Standards determined by TIA/CTIA in US
 IEEE standards often adopted
 Process fraught with inefficiencies and conflicts
 Worldwide standards determined by ITU-T
 In Europe, ETSI is equivalent of IEEE
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Emerging Systems
 4th generation cellular (4G)
 OFDMA is the PHY layer
 Other new features and bandwidth still in flux
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Ad hoc/mesh wireless networks
Cognitive radios
Sensor networks
Distributed control networks
Biomedical networks
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Ad-Hoc/Mesh Networks
Outdoor Mesh
ce
Indoor Mesh
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Design Issues
 Ad-hoc networks provide a flexible network
infrastructure for many emerging applications.
 The capacity of such networks is generally
unknown.
 Transmission, access, and routing strategies for
ad-hoc networks are generally ad-hoc.
 Crosslayer design critical and very challenging.
 Energy constraints impose interesting design
tradeoffs for communication and networking.
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Cognitive Radios
 Cognitive radios can support new wireless users in
existing crowded spectrum
 Without degrading performance of existing users
 Utilize advanced communication and signal processing
techniques
 Coupled with novel spectrum allocation policies
 Technology could
 Revolutionize the way spectrum is allocated worldwide
 Provide sufficient bandwidth to support higher quality and
higher data rate products and services
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Cognitive Radio Paradigms
 Underlay
 Cognitive radios constrained to cause minimal
interference to noncognitive radios
 Interweave
 Cognitive radios find and exploit spectral holes to avoid
interfering with noncognitive radios
 Overlay
 Cognitive radios overhear and enhance noncognitive
radio transmissions
Knowledge
and
Complexity
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Wireless Sensor Networks
Data Collection and Distributed Control
•
•
•
•
•
•
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Smart homes/buildings
Smart structures
Search and rescue
Homeland security
Event detection
Battlefield surveillance
Energy (transmit and processing) is the driving constraint
Data flows to centralized location (joint compression)
Low per-node rates but tens to thousands of nodes
Intelligence is in the network rather than in the devices
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Energy-Constrained Nodes
 Each node can only send a finite number of bits.
 Transmit energy minimized by maximizing bit time
 Circuit energy consumption increases with bit time
 Introduces a delay versus energy tradeoff for each bit
 Short-range networks must consider transmit,
circuit, and processing energy.
 Sophisticated techniques not necessarily energy-efficient.
 Sleep modes save energy but complicate networking.
 Changes everything about the network design:
 Bit allocation must be optimized across all protocols.
 Delay vs. throughput vs. node/network lifetime tradeoffs.
 Optimization of node cooperation.
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Green” Cellular Networks
Pico/Femto
Coop
MIMO
Relay
How should cellular
systems be redesigned
for minimum energy?
Research indicates that
significant savings is possible
DAS
 Minimize energy at both the mobile and base station via
 New Infrastuctures: cell size, BS placement, DAS, Picos, relays
 New Protocols: Cell Zooming, Coop MIMO, RRM, Scheduling,
Sleeping, Relaying
 Low-Power (Green) Radios: Radio Architectures, Modulation,
coding, MIMO
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Distributed Control over Wireless
Automated Vehicles
- Cars
- Airplanes/UAVs
- Insect flyers
Interdisciplinary design approach
•
•
•
•
Control requires fast, accurate, and reliable feedback.
Wireless networks introduce delay and loss
Need reliable networks and robust controllers
Mostly open problems: Many design challenges
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Applications in Health,
Biomedicine and Neuroscience
Neuro/Bioscience
Body-Area
Networks
Doctor-on-a-chip
Wireless
Network
- EKG signal
reception/modeling
- Information science
- Nerve network
(re)configuration
- Implants to
monitor/generate signals
-In-brain sensor networks
Recovery from
Nerve Damage
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Main Points
 The wireless vision encompasses many exciting systems
and applications
 Technical challenges transcend across all layers of the
system design.
 Cross-layer design emerging as a key theme in wireless.
 Existing and emerging systems provide excellent quality
for certain applications but poor interoperability.
 Standards and spectral allocation heavily impact the
evolution of wireless technology
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